Solo: A Star Wars Story: Who is Phoebe Waller-Bridge's character L3-37?

SOLO: A STAR WARS STORY brings together old friends and new foes for Star Wars fans all over the world. One of the additions to the Star Wars family was the outspoken L3-37. And if you recognised her voice from Fleabag, you'd be spot on. But who is Phoebe Waller-Bridge's droid character?